The preferred embodiments described herein relate generally to medical devices for repairing body vessels. More particularly, they relate to medical blood perfusion devices for repairing damaged body vessels and gaining hemostasis during emergency medical procedures.
Emergency or trauma physicians frequently encounter patients having traumatic injury to a body vessel, such as lacerated vessels or even transected vessels, resulting from gunshots, knife wounds, motor vehicle accidents, explosions, etc. Significant damage to a body vessel may expose a patient to deleterious conditions such as the loss of a limb, loss of function of a limb, increased risk of stroke, impairment of neurological functions, and compartment syndrome, among others. Particularly severe cases of vascular injury and blood loss may even result in death. In such severe situations, the immediate goal is to obtain hemostasis while maintaining perfusion of adequate blood flow to critical organs, such as the brain, liver, kidneys, and heart.
Examples of treatment that are commonly performed by emergency or trauma physicians to treat body vessel injuries include clamping the vessel with a hemostat, use of a balloon tamponade, ligation of the damaged vessel at or near the site of injury, or the insertion of one or more temporary shunts. However, conventional surgical repair is generally difficult with such actively bleeding, moribund patients. In many instances, there is simply not enough time to repair the body vessel adequately by re-approximating and suturing the body vessel. In many situations, the emergency physician will simply insert a temporary shunt (such as a Pruitt-Inahara Shunt) into the vessel. However, use of temporary shunts has been linked to the formation of clots. This may require returning the patient to the operating room for treatment and removal of the clots, often within about 36 to 48 hours of the original repair. Since shunts are generally placed as a temporary measure to restore blood flow and stop excessive blood loss, the shunt is typically removed when the patient has stabilized (generally a few days later) by a specialized vascular surgeon. After removal, the vascular surgeon will replace the shunt with a vascular graft, such as a fabric graft that is sewn into place. Ligation of the damaged blood vessel may result in muscle necrosis, loss of muscle function, or a potential limb loss or death.
Due to the nature of the body vessel injury that may be encountered, the use of shunts, repairing and/or ligating of a blood vessel often requires that such treatments be rapidly performed at great speed, and with a high degree of physician skill. Such treatments may occupy an undue amount of time and attention of the emergency physician at a time when other pressing issues regarding the patient's treatment require immediate attention. In addition, since the level of particularized skill required may exceed that possessed by the typical emergency physician, particularly traumatic episodes may require the skills of a physician specially trained to address the particular trauma, such as a vascular trauma, and to stabilize the patient in the best manner possible under the circumstances of the case.
U.S. Patent Publication No. 2007/0027526 A1, incorporated by reference herein in its entirety, discloses a device for repair of damaged portions of a body vessel. One device depicted in FIG. 1 of the patent publication includes a cylindrical conduit body 12, having a fitting 14 disposed at either or both axial ends of the cylindrical body. This device is suitable for placement within a blood vessel for repair of vascular trauma and restoration of blood flow through the vessel. One end of the fitting can be snugly received within the lumen of the cylindrical body, and one or more sutures 18 can be tied around the circumference of the cylindrical body to secure the fitting firmly to the cylindrical body along a first recess. When the device is positioned in the vessel undergoing repair, one or more sutures 20 are tied around the vessel at an exposed portion of the fitting along a second recess 16, as shown in FIG. 5, to secure the vessel to the fitting. The device depicted in the 2007/0027526 A1 publication is believed to be effective in repairing damaged vessels utilizing open surgical techniques in an emergency situation. However, since the device utilizes sutures to affix the damaged tissue portions to the fitting, the emergency physician must take time to tie the sutures properly. Although in modern medicine sutures can be tied in relatively rapid fashion, any step in a repair process that occupies physician time in an emergency situation is potentially problematic. Therefore, efforts continue to develop techniques that reduce the physician time required for such techniques, so that this time can be spent on other potentially life-saving measures.
In addition to the foregoing, the use of sutures to affix the vessel to the fitting compresses the tissue of the vessel against the fitting. Compression of tissue may increase the risk of necrosis of the portion of the vessel tissue on the side of the suture remote from the blood supply. When present, necrosis of this portion of the vessel tissue may result in the tissue separating at the point of the sutures. In this event, the connection between the vessel and the fitting may eventually become weakened and subject to failure. If the connection fails, the device may disengage from the vessel.
Another device 40 is depicted in FIG. 6 in the 2007/0027526 A1 publication and includes an expandable cylindrical body 44, having a fabric graft 45 covering the stent body. Barbs 43 can be provided along a portion of the circumference of the stent body to anchor the device into the vessel, and are shown extending through the fabric graft. Device 40 can be delivered with a conventional delivery sheath 42 as shown in FIGS. 8-10.
U.S. Patent Publication No. 2005/0038502 A1 describes a docking head that is mounted on a graft having an outer diameter so as to couple the graft to a blood vessel without requiring the use of sutures. The docking head includes a hollow truncated cone having a passage that is adapted to correspond to the outer diameter of a graft and a plurality of outwardly pointing and inclined barbs. The barbs may be flexible and inclined opposite a truncated end of the hollow truncated cone and are 1 to 4 times the thickness of the wall of the blood vessel. The inclined barbs are arranged at the circumference of the conical structure in at least one row and are distally pointed to the direction of the graft's body. In operation, the conical structure followed by the graft is inserted into neck through its narrow end while inclined barbs smoothly pass through a portion of the neck. Upon pulling back the conical structure, inclined barbs are embedded within the neck, forming a firm and sealed connection between the vessel and the graft.
While the outward facing barbs may facilitate secure placement of graft by securing the truncated cone portion within a body vessel, the particular design of the outward facing barbs presents drawbacks. First, these inclined barbs extending from the outer surface of the docking head, for example as shown in FIGS. 14 and 15, may engage body tissue away from the intended point of treatment during placement of the device. The tendency of the barbs pointing outwardly to engage tissue or other surfaces inadvertently can present a challenge during emplacement of the graft. Second, once in place within a body vessel, these barbs are not sized to penetrate an optimal distance into the wall of the body vessel. For example, FIG. 19 shows barbs 404 penetrating through the entire wall of a body vessel, which can lead to undesirable complications, such as bleeding and/or thrombus formation.
Emergency physicians generally know how to use a stent delivery catheter. Accordingly, when encountering patients having traumatic injury to a body vessel, it would be desirable for the emergency physician to deliver a medical device with a conventional stent delivery catheter to repair the injured body vessel. Thus, it would be desirable to provide a device for use in repair of an injured body vessel, such as an artery or a vein, during emergency surgery in a manner that is time effective, that addresses the trauma at hand to the extent possible, and that utilizes techniques that may be readily practiced by an emergency physician. In addition, it would be desirable if the device utilized during emergency surgery can be permanently placed within the patient, thereby obviating a need for subsequent surgical intervention. It is also desirable to provide a medical device having inclined barbs that are shielded from inadvertent contact with body tissue by a delivery system during the delivery process, and/or barbs adapted to penetrate only a portion of the wall of the body vessel required to secure the medical device within the body vessel.